<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<script>
		 var width=15;
		 var height=10;
		 alert(height);
		 var a="sss";
		 alert(typeof(a));
		 a=24;
		 alert(typeof(a));
		 a=3>6;
		 alert(typeof(a));
		 a=33.5;
		 alert(typeof(a));
		 a=null;
		 alert(typeof(a));
		 a="sss";
		 alert(typeof(a.changdu));
		</script>
	</head>
	<body>
	</body>
</html>
